To amplify on L-1, the appeal is not another trial de novo. It is held on the transcript and you have to point out legal mistakes made in the trial. The veracity of the testimony needed to have been noted at the time. Then perhaps it was a appealable error. You can't come now and show evidence (let alone the mere assertion) that the officer was mistaken (or lying). The fact your friend got off on a technicality wouldn't have made a difference even at the original trial, let alone at the appeal.